EPA’s MESA Air Study Confirms that Air Pollution Contributes to the #1 Cause of Death in the U.S.

By Dr. Wayne Cascio

This week we took a giant leap forward in our understanding of the relationship between air pollution and heart disease with the publication of results from the Multi-Ethnic Study of Atherosclerosis Air Pollution Study (MESA Air) in the leading medical journal The Lancet.

medical graphic of a coronary artery

Fat accumulation in the wall of a coronary artery

For more than two decades, scientific evidence has shown fine particle pollution (PM2.5) in the outside air is a cause of cardiovascular illness and death, and has justified improving the PM2.5 annual National Ambient Air Quality Standard to protect public health.  Yet, MESA Air was the first U.S. research study to examine a group of people over a period of 10 years and measured directly how long-term exposure to air pollution contributes to the development of heart disease and can lead to heart attacks, abnormal heart rhythms, heart failure, and death.  MESA Air did just that, and Dr. Joel Kaufman, the leader of MESA Air at the University of Washington and his colleagues should be commended for their accomplishment.

MESA Air was funded by EPA and made possible by the National Heart, Lung, and Blood Institute, which supports  a larger study on atherosclerosis called MESA. The additional air pollution study had the ambitious goal of seeking an answer to the question of whether long-term exposure to PM2.5 and nitrogen oxides (NOx) was associated with the development and progression of cardiovascular disease.  A total of 6,800 people with diverse racial and ethnic backgrounds and residing in six locations throughout the country agreed to participate in the decade-long study by researchers at the University of Washington who received the grant.  And the results are in!

The researchers used computerized tomography imaging to measure coronary artery calcium content in the same person repeatedly during the study as an indication of coronary artery disease. The results showed that long-term exposure to PM2.5 and NOx increased coronary artery calcium. The increase observed is at a rate that, over the period of the study, would change the risk of heart attack in some.

This study is extraordinary in many ways. First it provides the strongest evidence yet that air pollution can and does contribute to cardiovascular disease–the number one killer of Americans and people in developed countries throughout the world.  Secondly, the results define the relationship between air pollutants and the progression of coronary artery disease over time.  This relationship will help estimate the long-term health impacts and economic burden of air pollution within our population.   And, third the study shows the power of intra-agency cooperation to conduct valuable and cost-effective science.

The findings of MESA Air will continue to reverberate throughout the environmental science and public health communities for some time, but it’s time for healthcare providers, air quality managers and state and local planners to take note and to begin to consider long-term exposure to air pollution as having long-term health implications, even at levels near the National Ambient Air Quality Standards.

About the Author: Dr. Wayne Cascio spent more than 25 years as a cardiologist before joining EPA’s Office of Research and Development where he now leads research on the links between exposures to air pollution and public health, and how people can use that information to maintain healthy hearts.

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